A transformer has become an essential electronic component for voltage regulation into required voltages for various kinds of electric appliances. Referring to FIG. 1, a schematic exploded view of a conventional transformer is illustrated. The transformer 1 principally comprises a magnetic core assembly 11, a bobbin 12, a primary winding coil 13 and a secondary winding coil 14. The primary winding coil 13 and the secondary winding coil 14 are overlapped with each other and wounded around a winding section 121 of the bobbin 12. An insulating tape 15 is provided for isolation and insulation. The magnetic core assembly 11 includes a first magnetic part 111 and a second magnetic part 112. The middle portion 111a of the first magnetic part 111 and the middle portion 112a of the second magnetic part 112 are embedded into the channel 122 of the bobbin 12. The primary winding coil 13 and the secondary winding coil 14 interact with the magnetic core assembly 11 for voltage regulation.
Although the transformer 1 is effective for power conversion, there are still some drawbacks. For example, since the heat generated by the transformer 1 is dissipated away via a natural convection mechanism, the magnetic core assembly 11 and the winding section 121 of the bobbin 12 are exposed in order to increase the heat-dissipating efficiency. Under this circumstance, the transformer 1 readily generates electromagnetic interference (EMI), which adversely affects the neighboring circuits. Generally, additional high-level filters are used for suppressing EMI. The uses of the filters increase complexity of the circuitry layout and the fabricating cost.
In a case that the transformer 1 is used in a poorly ventilated environment, the heat generated by the transformer 1 is accumulated and the temperature of the transformer 1 is gradually increased because the heat is difficult to be transferred to the ambient air. The elevated temperature of the transformer 1 may result in damage of the transformer 1 and/or the electronic components neighboring the transformer 1. Under this circumstance, the performance and the use life of the transformer 1 and/or the whole electronic appliance will be deteriorated. Therefore, in designing a transformer, it is important to enhance the heat-dissipating efficiency of the transformer.
For increasing the heat-dissipating efficiency of the transformer 1, some measures are taken. For example, the material of the magnetic core assembly 11 is improved, the diameters and/or the coil turns of the primary winding coil 13 and the secondary winding coil 14 are modified, or the primary winding coil 13 and the secondary winding coil 14 are replaced by copper foils to increase the heat transfer area. Since the transformer structure is altered, a new mold of the transformer should be designed and made. The process of designing and making the new mold of the transformer increases extra cost.
Therefore, there is a need of providing a transformer having enhanced heat-dissipating efficiency and reduced electromagnetic interference so as to obviate the drawbacks encountered from the prior art.